Pneumatic pumping system



Dec. 14, 1948. c. YEOMANS PNEUMATIC PUMPING SYSTEM 2 Sheets-Sheet l Filed Jan. 19, 1946 INVENTOR. fiarZes' yeaizzams' C. YEOMANS PNEUMATIC PUMPING SYS TEM Dec. 14, 1948.

2 Sheets-Sheec 2 Filed .Jan. 19, 1946 W LL f Patented Dec. 14, 1948 PNEUMATIC PUMPING SYSTEM Charles Yeomans, Hubbard Woods, Ill., .assigncr .to'Yeoznans Brothers Company, Chicago, ill, a corporation of Delaware Application January 19, 1946, Serial No. 642,243

6 Claims. 1

This invention relates to a method and an apparatus or system for pneumatically pumping relatively coarse materials such as sewage screenings and the like.

The pneumatic pumping of materials containing a high percentage of liquids, for example raw sewage, by the use of pneumatic ejectors, has been practiced. for many years. cludes a receiver having inlet and outlet openings, which are adapted to be closed by the use of'suitably arranged flap valves, and an air connection which is adapted to be connected either to a suitable source of pressure air'or to an airvent. There is also provided control means which is operable in response to thefilling oi the ejector receiver to close the vent means and to admit air under pressure to the. interiorfof the receiver through the air connection. This air :efi'eots the discharge of the contents of the receptacle by pneumatic pumping action, the flap'valves being operable to close the receiver inlet/and to open the receiver outlet when the pressure is applied. The control means'is further operable when the receiver contents have been discharged 'to shut off the pressure air and'tovent the interior of the receiver in order that it maybereflll'ed and the cycle repeated. i Y l The receiver inlet valve is closed during the ejection operation in order-tolpreventi the air pressure from being transmitted to the inlet line,

and during the filling operation it is necessary that the inlet valve shall be open and that the outlet valve shall betightly closedin'. order to prevent back-flow of the-previously discharged material. w r 1 Pneumatic ejector systems as described above are reliable and most satisfactory in. operation and, as previously stated, have been.v extensively used for the pumping of materials such as raw sewage. Despite this use and the known advantages of pneumatic ejectortype pumping equipment, little use has been made of such systems for the pumping of coarse materials such aszsewage screenings, and the principal object of the present invention is. toprovidea. pneumatic pumping system which is capable of .efii'ciently and reliably handling coarse materials of. this character. l

During the course. of. my investigation of the problem, I have discovered. that: coarse; sewage screenings of the average type can be successfully and reliably pumped in a pneumatic ejector system, provided that the inlet and outlet. openings in the ejector receiver are of lar eeross-sectional area, and provided. that allow velocity through about two feet per second is maintained during each inflow and outflow operation. This combination of structural and operational characteristics effectively prevents fouling of the inlet and outlet valves with resultant back-flow from the outgoing line or application of pressure to the A further and more specific object of my invention is to provide a pneumatic ejector system in accordance with the above stated principal. object,

Whichcan be assembled from conventional and As will hereinafter appear, the objects of the invention are accomplished by the provision of an ejector system which obtains high rates of. flow at the outlet valve opening by the obtainable with standard available equipment,

to prevent the filling and cyclic operation of the ejector equipment except when the air supply is completely adequate for accomplishing the desired high speed ejection of the contents of the The system thus permits the use of air compressors and. air storage tanks of moderatedimensions, and, provided that the daily or .hou-rly capacity of the system is adequate to pump all of the material- Which is to be hand-led in that period, it makes no difference whether the inlet in relatively large amounts at any particular In other words, the apparatus is so arranged that it will receive and will-deliver materialonly as rapidly as it is able to handle that material at the high velocity which I have determined to be required in order to maintain the ejector in The features of the invention and its further various advantages will be made more apparent in the accompanying drawings and the following description of certain illustrative embodiments Fig. l is a diagrammatic illustration of apnea matic ejector system in accordance withgthe in Figs. 2 3 illustrate certain modifications of The system illustrated in 1 is designed parpneumatically pumping sewage screenings in accordance with the invention, and also sludge, and a sewage screening chamber of the Lip-flow type is illustrated in section at l, the screen or strainer included therein being indicated The .usual ejector inincoming line.

available parts.

use of compressed air in amounts and in pressures but which includes control equipment operable ejector receiver.

material to be pumped is delivered to the ejector time.

operative condition and prevent fouling.

thereof.

In the drawings.

vention; and

the system illustrated in Fig. 1.

9 ticularly for Raw sewage is delivered to the chamber l below the screen 2 and the liquid portions of the sewage, together with any fine suspended solids, flow upwardly through the screen 2 which is of such mesh that coarse particles contained in the sewage will be trapped below the strainer 2. A pipe line 3 connects with the bottom of the screening chamber l, which desirably slopes inwardly, for conducting the screenings collected therein to an inspection well 4, and the inspection well 4 is similarly connected by a pipe line 5 to the inlet side of a pneumatic ejector 6. the ejector 6 is connected by additional piping l to the inlet hopper 8 of a, digester 9 or to any other point to which the screenings are to be delivered by the ejector 6. In order that the ejector may be used for pumping sludge from the bottom of the digester, in accordance with the conventional pumping practice, an additional pipe line ill is provided for conducting sludge from the bottom of the digester to the inspection well 4.

It is the usual practice to pump screenings and sludge in a system of this type during only a short interval of each days run, or of each shift period, and to facilitate this, a manually operated valve II is provided at the delivery end of the screenings line 3 for controlling the delivery of screenings to the inspection well 6. An elongated operating handle [2 for the valve i I is provided to permit operation of the valve at the inspection well in conventional manner. The sludge line II) will be provided with suitable valves and connections so that the sludge may be re-circulated through the digester or may be pumped to settling tanks or elsewhere.

Except for the provision of inlet and outlet openings of large cross-sectional area, the ejector 6 is of conventional design and may be similar to that shown in Winter Patent 2,373.935, which is assigned to the assignee of this invention. The inlet valve I3 used in conjunction with the ejector 6 is preferably of the quick opening, shear-gate, type, and the relative proportion of the valve, ejector receiver, and other parts should be such that the inflow of the material to be pumped by the ejector will take place at a rate of flow at least equal to about two feet per second. Infi-ow, at this velocity is, of course, relatively easy to accomplish. The problem resides in the obtaining of proper outflow velocity.

' The outlet check valve illustrated at I i is of the hinged flap type and may be similar to the valve shown in the Winter patent. The cross-sectional area of both the inlet and outlet valves must, of course, be sufficient to permit free flow therethrough of the largest size material which the ejector may be called upon to handle.

The compressed air supply used for effecting the operation of the ejector includes an air compressor [5, which may be of the rotary type and which is arranged to deliver compressed air to a storage tank ll by means of suitable piping t6. A check valve [6a is provided in the line It from the compressor 15 to the storage tank ll in order to p vent back fiow of air when the compressor is not running.

Delivery of compressed air from the storage tank to the ejector pot or receiver is most conveniently controlled by means which is responsive to the level of the material contained within the ejector receiver, and various of the'eonventicnal control systems for effecting this type operation may be used. The particular apparatus disclosed in the system illustrated in Fig. l of the drawings includes an arrangement similar to that shown in the above-mentioned Winter patent. This con- The outlet side of 'trol system includes a piston valve [9 which is connected to the pressure air storage tank I! by a pipe line [8 and is connected to the interior of the receiver by means of pipe line 20 and a terminal section 2| formed integrally with the ejector. The piston valve 19 includes an internal piston which is movable between two extreme positions. In one position the piston valve operates to connect the air line 20 to the ejector to the air storage tank H by way of the pipe line l8, and in the other position, the piston valve I9 is operable to close the line [8 and to connect the ejector air line 221 to a vent line 21.

Operation of the piston valve 19 in response to changes in the level of the material contained within the ejector receiver is accomplished by means of a pilot or control valve 25, which is connected to a float provided within the ejector receiver by means of a float rod 22 and linkages 23 and 24. The pilot valve 25 is of the two-position type and is connected to the air supply and to either side of the piston valve l9 by means ofsuit: able pipe lines 26 of small diameter.

When the ejector empties, the float rod 22 moves" downwardly and operates the pilot valve 25 to supply air to the piston valve I9 so as to eifect the closing of the connection between the air line 20 and the line [B leading to the air storage tank H, and to open the connection between the air inlet line 20 and the vent line 21. Similarly, whenthe ejector fills, the float lifts the float rod 22 and opcrates the pilot valve 25 to cause the flow of pres.

sure air through the lines 25, whi-chefiects operatlon of the piston valve l9 to the other extreme position. In thispositlon,.the air line 20 is connected to theair storage tank, and the connec-r tion to the vent line 2! is closed.

It will be apparent that in the system'as' de scribed, the ejector 6 is in condition to refill im-. mediately following each ejection operation,,regardless of the conditions in any other part of the system. In instances where the apparatus is used for pumping screenings or other material available in considerable quantity at intermittent intervals, this inherent capability of the system to initiate immediately an automatic repetition of the operative cycle would be very undesirable.v

Immediate repetition of the cycle requires, if high flow speed operation in accordance with the invention is to be obtained, that the system include air supply equipment of suflicient capacity to provide air, at the relativelyhigh pressure required, in the very short interval of time whichelapses between successive operations :of the ejector. The difiiculties are cumulative, because in order to avoid clogging, it is desired to maintain flow speeds through the inlet and outlet valves of at least about two feet per second, yet the obtaining of this speed during ejection requires relatively large amounts of high pressure air, and the more efficient the system becomes from the viewpoint of preventing fouling and clogging of the outlet valve, the'more likely the system is to become clogged on the next successive operation, due tothe smaller total time interval involved in the complete operation.

The system of the invention thus includes, as previously stated, means for positively preventing the refilling and recycling operation of the ejection durin any period when there is insuflicient pressure air available to effect the discharge of the ejector receiver at the high flow velocities which I employ, in order to permit the use of: pneumatic pumping apparatus of this character for the pumping of coarse materials such'as sewshareware:

5 age screeningsy means comprises in the particular system illustrated; a'valve, such as: thediaphragm valve 30, whichis connected -in'the ejector ventline 21; and which is connected as by means'of a pipeline-29 m the' compressor I5" in such relation that thevalve is closed-- when-- ever the compressoris operating. The 'pressure to operate *the diaphragm valve 30 may be sup plied by means of an auxiliarypressureoutlet 28 embodied into the-compressor apparatus; as'sh'own' in my Patent 2,385,905,'-.which' was-issued'onOctober 2; 1945, or other equivalent arrangements maybe used.

The compressor I5 includesa driving motor" (not shown) which iscontrolled by 'meansof-apressure responsive' switch' 33 connected in pressure responsive relationshiptotheair' storage tank' I l by means of an airline- 34; Thee-Witch iii-includes a circuit-openin -and closing'element; which may be connected" as shown diagrammat ically in Fig. 1, to open and toc1ose the electrical circuit 35 from a-suitablesource of "power; tothe compressor motor through the-conductors 3| 'and' 32. The switch 33will normallybe setto'start" the compressor I5 when-the-pressure within'the air storage tankI I has dropped'a-relaitively small amount below that required for accomplishing the emptying of the'ejector'at the'desired high speed. Thus, immediately following the initiation of each ejection operation with resultant flowof air from the air storage tank I1into"t'l'1'e'-ejector receptacle via the piston valve I Hand'theair'inIet 20, the pressure responsive switch 33.'Will"be-op'-' erated to start the compressor I'I. Immediately,-

pressure will be applied to the di'aphragmvalve30- so as to close the vent line 21 from the piston valve i9, and this vent' line' will remain*closed" until the compressor hasstoppedi which; the: normal cycle of operation, will be sometime after the contents of the ejector have beenpneumatically ejected, and after" the pistonvalv'e I9 has been operated, in'response-to' lowering ofithe float connected to the float rod1322, to cl'ose'th'e'outlet line IB from the air storage tank and'to connect the air line 20 leadin to the'ejector to'tlievent line 21.

So long as the'vent line'21is closed), pressure will be maintained within'the ejector receiver, and this pressure will hold the inlet valve I3"closed,' effectively preventing the inflow. of any additional material into the ejectonreceiverh Moreover,. since the-openingof the diaphragm va1ve.30 in the vent line 21 is prevented so long ,astlie compressor is running, any additional "inflow is. preventecluntil the air supply has reached the point. where another high speedejection operation. can be carried out.

Various other arrangements inaccordancewith the invention may be employed." For example, in the modified arrangement shownin Fig. 2, the motor driven air compressor I5a islot a. more, conventional type and lacks the auxiliary pressure air outlet 28 of the compressor I5., Tlmdiaphragm valve 30 used in this modified I arrangem ment is operated by pressure air, taken from the air storage tank I! through the pipe-.li-ne 36.-in: which there is incorporateda solenoids control valve 31. The valve 31 hastwolpositions and-is so arranged that in one position pressure, airwvill be conducted from the storage-tank- II through the pipe line 36 to the'dia'phragm chamberzof'thezt valve 30, thereby closinggthe valve;v InLtherotherr position, which is thede-energized position-:ofithe: valve 31, the portion :Bfia of zthe air. linesleadingtfrom the air storage tankcI'L-to theithree-wayi valve fl will be sealdiofiiand' theiporti'on 39115 01? the-air li'ne leading from the valve Tto the dietphra'g-m' valve fll will b'e oonnectedito a vent w r- J I When the pressure responsive swltoh 38- i's ope erated"; in" responseeto the dc'crea se in "pressuree within theair 'storage tanlc I'llresulting from.the= initiation-of an ej ection' operation; tti'eeelectrical circuit theretlirougli is: closed? -'I lier'eupon tlrei" driving mot'or for tlie compressor I 5a1wi1l be em tion' ot'fthe pilot valve- 12 S' and'the pistorravalve';l9gs I the compressor I5a will continue'ztmirunz. until-r the desiredf air 'pressures: level' hasz beenr restored: Withimtherair: storage-ztankx lla At that point/1. therpr essure switch 33 vvill Toperatetoiopenttheicin cuit: therethrough,-. shutting-i ofli the: compressors motor; Simultaneously; thet-solenoidivalve'zi31will? valve: 301' has been replacedrbys an electrically operatedzvalve '4 I rwhichaisz normally lopeno and-.3 theienergizationtoffthisvalvesisicontrolledidirectly byrthepressure: responsivezswitch :33) So longfiasi thezpressure within ntheia-ir'istoraga tanki'is ib'el'owr theivalueidetermiried:necessary-to accomplishi-th'et desired I high speed: ejection of thei ejector-icontens; the valved-I willzremain;cl:osedrventing of; the; ejector-*receivew will be prevented; and? the: pressure thus; retained: within" the: receiver: will i prevent: the? inflow; of: additional; materlali r'A soonas Tthefpressure within: the storage tanka IL! I? hasszbeenz restored to =therdesireolEivalue; the-flown pressor motoricontrol .switclirsaa wi Jep'em The receiver will then .be*ventecl;. and hei-system will' be-inxconditi'onzfor:at-newroperatinnr.

In each of ithe:isystemssdescribedzrln the foregm' ing means is provided;for; p'ositively"preventing? the: refilling of' the: ejector: receiveriaand cyclic: operation 'of'thasystem, except whenpressure air iszzavailable at 'suificientpressure and in sufii 'cient amounts: to: assure: th-er ellectiom ofithe=: receiver:3 contentsi'ata'hig'htspeed: The iinventionithus per mits: therassembling otsainoveli pneum atia ejotor pumping system,- which is capable --ot lian g verytcoa'rse materials without danger f cl'o'g andrwhich does rrot irequire 'the use of othertlia i ordinary"capacity standard cornpressorso other-* than standard 1 auxiliary: equipment. The -features of I the ejection systemand 'of tlie nov'el methodiof operation- 0f a pneumatio'ejections I temawlfieh'rare madepossi-ble by theinvention ar set-:fortkr in :theaccompanying c-laims Iiclaimz the followiirg' as myrinvention.

1; In pneumatic ejector apparatus adaptedior theEpne-umatic pumping of 'sewag-e screeningSaar-1d other coarse material, a receiverhavingdriltarid outlet: openings F of large cros's-sectional area; a pressure air supply: 'systemrwl'i icli includes an'- air" storage tankg means responsivetothe lvel"of the" mat er-la-li'cont ainedwithirws aid-; r'eceiver for conw meeting said air storage tank to said receiver, y when said receiver becomes filled, to efiect the pneumatic discharge of the contents thereof, a vent means arranged for connection to said ejector to effect the discharge of pressure air therefrom following ejection operations, and means responsive to the air pressure within said air storage tankfor closing said vent means when said pressure is below a predetermined value, thereby preventing the escape of pressure air from said receiver and the flow of additional material into said receiver except when the pressure in said air'storage tank is above said pre-, determined value.

' 2. In pneumatic ejector apparatus adapted for the pneumatic pumping of sewage screenings and other, coarse material, a receiver having inlet and outlet openings of large cross-sectional area, a pressure air supply system which includes an air storage tank, means responsive to the level of the material contained within said receiver for 0011- necting said air storage tank to said receiver, when said receiver becomes filled, to effect the pneumatic discharge of the contents thereof, said dischargetaking place at a rate of fiow through the receiver outlet opening which is at least equal to-about two feet per second, provided that the pressure of the air contained within said storage tank exceeds'a predetemined minimum value at the beginning of the ejection operation, a vent meansarranged for connection to said ejector to efiect the discharge of pressure air threfrom following ejection operation, and means operable in response to the air pressure within said storage tank to close said vent means when said pressure is below said predetermined value, thereby preventing the discharge of pressure air from said receiver and the flow of additional material into said receiver, except when the pressure in said storage tank is above said predetermined value.

3. In pneumatic ejector apparatus adapted for the pneumatic pumping of sewage screenings and other coarse material, a receiver provided'with' inlet and outlet openings of large cross-sectional area and having fiap valves for closing said openings, a pressure air storage tank, a compressor connected to said storage tank, means responsive to the pressure within said air storage tank for controlling the operation of said compressor, level responsive, control means operable to connect said pressure air storage tank to said receiver, when said receiver becomes filled, to effect the pneumatic discharge of the contents thereof, said discharge taking place at a rate of fiow through the receiver outlet opening which is at least equal to about two feet per second, provided that the pressure of the air contained within said storage tank exceeds a predetermined minimum value at the beginning of the ejection operation, a vent line arranged for connectionto said receiver following'each ejection operation to effect the venting of pressure air from-said receiver, said level responsive control means being operable at the conclusion of each ejection operation to stop the flow of air from said air storage tank into said receiver and to connect said vent line to said receiver, and means responsive to the pressure within said air storage tank for preventing the venting and refilling-of said receiver except; when the pressure in said storage tank is above said predetermined value,

4. In pneumatic ejector apparatus adapted for the pneumatic pumping of sewage screenings and other coarse material, a receiver provided with inlet and outlet opening$ of large cross-sectional area, a pressure air supply which includes an air storage tank and a compressor having a -main' outletv opening connected to said storage tank and an auxiliary outlet opening, means responsive to the pressure within said air storage tank for controlling the operation of said compressor,

level responsive, control means operable to connect said pressure, air storage tank to said'receiver, when said receiver becomes filled, to effect the pneumatic discharge of the contents thereof at a predetermined high speed, provided that the pressure of the air contained within said storage tank exceeds a predetermined minimum value at the beginning of the ejection operation, vent means arranged for connection to said receiver following each ejection operation to efiect the venting of pressure air from said receiver, said level responsive control means being operable at the conclusion of each ejector operation to stop the flow of air from said air storage tank into said receiver and to connect said vent means to said receiver, and pressure responsive means con-' nected to the auxiliary outlet of said compressor for preventing the venting and refilling of said receiver when said compressor is in operation, the

pressure responsive means for controlling the operation of said compressor being operable to initiate operation of said compressor when the pressurein said air storage tank drops below said minimum value.

5. In pneumatic ejector apparatus adapted for the pneumatic pumping of sewage screenings and othercoarse material, a receiver provided with inlet and outlet openings of large cross-sectional area, a pressure air supply which includes an air storage tank and a compressor having a main outlet opening connected to said storage tank and an auxiliary outlet opening, means responsive tothe pressure within said air storage tank for controllin the operation of said compressor, level responsive, control means operable to connect said pressure air storage tank to said receiver, when said receiver becomes filled, to efiect the pneumatic discharge of the contents thereof at high speed, said discharge taking place at a rate of fiow through the receiver outlet opening which is at least equal ,to about two feet per second, provided that the pressure of the air contained within said storage tank exceeds a predetermined minimum value at the beginning of the ejection operation, a vent line arranged for connection to said receiver following each ejection operation to effect the venting of pressure air from said receiver, said level responsive control means being operable at the conclusion of each ejectionoperation to stop the flow of air from said air. storage tank into said receiver and to connect said vent line to said receiver, and means including a diaphragm valve which is connected in said vent line and which is arranged to be operated by pressure from the auxiliary outlet of said compressor for preventing'the venting and refilling of said receiver when said compressor is in operation, the pressure responsive means for controlling the operation of said compressor being operable to initiate operation of said compressor when the pressure in said air storage tank drops below said minimum value.

6. In pneumatic ejector apparatus adapted for the pneumatic pumping of sewage screeningsand other coarse material, a receiver having inlet and outlet openings of large cross-sectional area, a compressed airstorage tank connected to said receiver, means operable, when the material contained in said receiver reaches a predetermined level, to admit compressed air from said tank into said receiver, thereby to effect the discharge of said material through said receiver outlet openv ing, means including an exhaust valve for venting compressed air from said receiver following each ejection operation, and a control for said exhaust valve which is operable, in response to the pressure in said storage tank, to hold said exhaust valve closed and thereby maintain a positive pressure in said receiver, thus preventing the inflow of material into said receiver through said inlet opening during periods when the pressure in said storage tank is below a predetermined value.

CHARLES YEOMANS.

10 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

